Conventional trigonal cone- and saw teeth-like roll grinding blades have a drawback that the product recovery rate is lowered as the grinding efficiency is increased.
That is, the roll grinding blades for the production of sweet potato starch have trigonal cone-like blade elements set to a rotational roll made of highly soft steels, in which the best starch recovery rate is obtainable when the easily abrading blade elements are abraded such that the crests of the trigonal cones are abraded by about one-half into a trapezoidal shape. However, the blade elements abraded to the trapezoidal shape involve a defect that not only the grinding efficiency is reduced but also they fail to perform complete grinding, for example, by yielding chips, i.e., waste pieces of potatoes, thus requiring re-grinding by a grinder.
There has been a roll grinding machine for the production of Irish potato starch having saw teeth-like grinding blades which can detachably be mounted to a roll but, since the saw teeth-like shape undergoes a great resistance and requires abrasion, it has a defect that the detaching and attaching device to the roll is complicated to increase the cost and that it can not be utilized for the production of sweet potato starch because of the low product recovery rate.
Grinding of root crops, fruits, vegetables, etc. by a grinder for the production of processed food or juice therefrom involves a demerit of poor fabrication efficiency.
The cutter of a juicer also has a defect that the blade elements, being of a trigonal cone- or trigonal plate-like shape, are not satisfactorily bite into the material to be processed and are abraded rapidly.
The rotational blade shown in Japanese Patent Application No. Sho 59-037431 also has a drawback that the grinding efficiency is reduced if the starch recovery rate is increased.
That is, all of the conventional grinding blades have a conflicting relationship between the product recovery rate and the grinding efficiency. Therefore, they are defective in that the grinding efficiency can not be improved.
The conflicting relationship between the product recovery rate and the grinding efficiency is caused by that all of the blade elements of the conventional grinding blades are mono-layered blades.
The object of this invention is to overcome the problems in the drawbacks of the conventional mono-layered blades and provide a grinding blade capable of improving the grinding efficiency remarkably without reducing the quality or the recovery rate of products.